Effect of Kiwi Shell and Incubation Time on Mobility of Lead and Cadmium in Contaminated Clay Soil

Abstract

In this study, the effectiveness of kiwi shell was investigated to reduce the mobilityof Lead and Cadmium in clay soil in different intervals. For this purpose a clay soil sample wascontaminated with Lead and Cadmium in distinct dishes with 10 and 600 ppm concentrationsrespectively and mixed with 5% kiwi shell. Samples were placed in incubator, and then samplingof soil in incubator was performed in intervals 3 hours, 1, 3, 7, 14, 21 and 28 days. Heavy metalsconcentrations were determined in different fractions of soil including exchangeable, carbonate,Fe-Mn oxides, organic matter, and residual with sequential extraction procedure and atomicabsorption spectrophotometry. The results showed that during incubation, Lead concentration intreatments with kiwi shell rather than control soil increased in carbonate from 19.48 to 26.18 andin organic matter from 9.06 to 18.66 percent. Exchangeable, Fe-Mn oxides and residual fractionsdecreased from 11.48 to 6.69, 45.72 to 39.83 and 14.21 to 7.90 percent respectively. In sampleswith absorbent compared with control soil, Cadmium concentration in carbonate and organicmatter increased from 28.20 to 38.40 and 18.76 to 24.72, while in exchangeable, Fe-Mn oxides andresidual decreased from 16.66 to 13.69, 37.25 to 19.65 and 6.24 to 3.61 percent respectively. Thisstudy revealed that kiwi shell function in decreasing Cadmium and Lead mobility in studied claysoil were increased with increasing incubation time, but Cadmium compared with Lead requiredadditional time to transfer and mobility to constant and stable soil fractions such as, organic matterand Fe-Mn oxides.